Multiple Antenna Element Approach to a Combined Precision Attitude Determination and GPS Anti-Jamming/Spoofing Capability

A multichannel GPS system, with associated Controlled Radiation Pattern Antenna Array (CRPA) design, will provide continuous position and attitude determination. This system supports L1/L2 and SAASM or M-Code modes under both GPS jamming, and spoofing attack, to maintain navigation and attitude in contested environments. The system uses direction finding to determine angle of arrival (AOA for the satellites, jammers and spoofers.Real-time adaptive beamforming algorithms are used to direct beams toward GPS satellites and adaptive nulls toward jammers and spoofers, thus providing protection for the GPS satellite signals.We will investigate compatibility with SAASM as well as M code GPS receivers, develop simultaneous capabilities for L1 and L2 frequencies, expand testing capabilities and investigate related applications such as jammer/ spoofer AOA estimates.The measured azimuth and elevation for each signal is compared to the expected angle of arrival of the GPS satellite signals, as computed from the ephemeris. Agreement between measured angle of arrival and computed angle of arrival indicates legitimacy. If the measured angles of arrival of do not match the expected angles, a spoofed signal is indicated. As long as the signals are legitimate, differential carrier phase across baselines is used by the system to calculate platform attitude.